Your provider may order blood tests to confirm your diagnosis. The blood will be sent to the lab to check the level of several substances, including CA-125. CA-125 is a substance found on the surface of ovarian cancer cells and on some normal tissues. A high CA-125 level could be a sign of cancer or other conditions. The CA-125 test is not used alone to diagnose ovarian cancer. This test is approved by the Food and Drug Administration for monitoring a woman’s response to ovarian cancer treatment and for detecting its return after treatment.